Object detection devices are known which periodically transmit probe waves such as millimeter waves over a predetermined range of angles around a vehicle, and detect an object around the vehicle upon receiving reflected waves.
In a vehicle equipped with an object detection device of this type, the position, azimuth, and relative velocity of another vehicle (a preceding vehicle) present ahead of the own vehicle in its direction of travel are calculated, and the speed of the own vehicle is controlled accordingly to maintain a constant distance therebetween (see PTL 1).